Being "in touch" has become increasingly important for some people, i.e., doctors, business executives, attorneys, sales people, etc., who have a strong need to be reached wherever they are. Many of these people have a telephone for business, for home, a cellular telephone for the car, and/or a transportable cellular telephone that can be carried around when that person is not near one of the other telephones. Additionally, many of these professionals travel frequently but still need to be reached.
For these people, the telephone industry introduced several programs which permit these individuals to keep in touch. For example, AT&T has a "Follow Me" service wherein, when the person subscribing to the service has one telephone number (i.e., 700-555-1234), and regardless of where the person is, he or she may be reached at that telephone number.
However, such services require that the subscriber call in to the service every time he or she changes location in order to register the telephone number at which the subscriber may be reached. Such registration usually requires the subscriber to dial a predefined number, enter a PIN or some form of identification, and then enter the telephone number of the telephone where he or she can be reached. Therefore, when the subscriber leaves his or her office and turns on a mobile telephone unit, the subscriber has to call in and register the telephone number of the mobile unit. When the person arrives at a destination, he or she has to register a new telephone number. Such constant registration of telephone numbers can be annoying to the subscriber, especially when he or she only uses the mobile unit for short periods of time (i.e., local trips). Thus, some people who could benefit from a universal telephone number do not subscribe or underutilize such a service, because it can be cumbersome to register the current reach number when the user changes from land-based to mobile frequency.